Break-even: where profit starts

Some months you work hard and still lose money, and it feels like a mystery. It isn't. Every business has a line on the calendar where the fixed costs are finally paid off — before it, every job funds the rent; after it, jobs fund you. That line has coordinates, and you can compute them.

Split your costs in two

• Fixed costs don't move with workload: the $2,500 month from lesson 2.
• Variable costs exist only when a job does: its materials, its labor.

Take a shop whose average job sells for $1,000 and consumes $700 of materials and labor. Each job contributes what's left:

$\text{contribution margin} = \$1{,}000 - \$700 = \$300 \text{ per job}$

Contribution margin is the most underrated number in small-business math. It is NOT profit — it's the piece of each job available to chip away at the fixed pile.

Where the lines cross

$\text{break-even} = \frac{\text{fixed costs}}{\text{contribution margin}} = \frac{\$2{,}500}{\$300} \approx 8.3 \text{ jobs per month}$

Jobs one through eight of the month earn you nothing — they pay rent, insurance, and the truck. The month's profit lives entirely in jobs nine, ten, and eleven. That is why a slow month hurts so much more than one-eleventh per missing job: the jobs you lose are always the profitable ones at the end.

What the picture is for

Break-even turns three vague anxieties into checkable numbers:

• "Can I survive on N jobs a month?" — If N is below 8.3, no, not at these prices and costs. Change a number, not your hopes.
• "Should I take this low-price job?" — Anything priced above its variable cost adds SOME contribution — but a calendar filled below break-even is a treadmill. Fill gaps with it; don't build on it.
• "What does a fixed cost really cost?" — A $300/month software stack is one full extra job every month, forever, before you profit. Judge subscriptions in jobs, not dollars.

One more use: raise the price to $1,100 and the contribution margin jumps to $400 — break-even drops to 6.3 jobs. That asymmetry, price versus volume, is the next two lessons.